The invention relates to a composite tape adapted to be secured to an object and, when removed from that object, to provide a visible indication ("message") on the object which was not theretofore visible, which tape can be readily applied to a successive plurality of such objects by means of mechanical equipment. A primary, but not exclusive, use for such a tape is to indicate when the security of the object to which it has been attached has been compromised.
The security of objects shipped from one place to another is extremely important, and represents a very significant problem. Far too often packages are opened in transit and the contents surreptitiously removed. Shipments destined for particular destinations such as foreign countries are wrongfully re-routed. Unbroken chain of custody for forensic evidence must be established. Almost every company has some level of exposure to industrial theft, diversion, tampering or pilferage. Industry today expends vast sums in an attempt to meet these problems.
One approach that has had considerable success has been to provide a tape designed to be secured to an object such as a package, which tape has one appearance when thus applied, but produces a different and distinctive appearance if the tape has been removed, even when an attempt is made to re-apply the tape. For example, if such a tape is used for the sealing of a package to prevent access to the contents of the package, surreptitious removal of the tape will create that different appearance, such as the display of a warning word such as "Void".
Since tapes of the type in question are commonly used as sealing tapes for cartons, applied over the joints of such cartons to hold flaps in place and thus protect the contents of the cartons from pilferage, they are sufficiently substantial in nature to accomplish that result. Usually, in the form in which they are applied, they transmit certain intelligence to viewers, such as a trademark, a logo, or other information such as "Fragile" or "This Side Up". When they are removed from the container in order to provide access to the contents, however, they leave behind on the container some indication, such as the words "Void" or "Opened", to indicate that the container has been tampered with, and this is done in such a way as, for all practical purposes, to prevent re-application of the tape to the container from obscuring that revealed indication. This conventionally involves taking a backing sheet of sufficient structural integrity to function as a carton seal and applying thereto coatings which can accomplish the desired result. The nature of those coatings and the ease or difficulty of applying them to the backing sheet constitute significant industrial problems.
Such a tape has on one exposed surface a layer of adhesive by means of which the tape is secured to the container or other object to which it is applied. In most applications tapes of this type are employed to seal a large number of successively presented containers, so that as a practical matter a very great length of tape must be initially provided. The only practical way for providing such an extreme length of tape is in the form of a roll, but that means that the adhesive layer exposed on one turn of tape is pressed against and tends to stick to the other exposed surface of the next adjacent turn of tape in the roll. Accordingly the exposed adhesive coating has been provided with a sheet of lining material which separates the adhesive coating from the adjacent turn of the tape and thus prevents the two from sticking together. However, the use of such a separating lining sheet involves significant problems. In the first place, that separating sheet adds weight and bulk to the roll of tape, thus limiting the size of rolls which can be handled even by machinery. By eliminating the separating sheet rolls of tape as long as 3-4000 lineal feet are made practical. In the second place, the separating sheet must be removed from the tape before the tape is applied to the carton which it is to seal and then discarded. This not only involves action on the part of the operator which reduces his efficiency, but also involves the use of extra material. In the third place, and most significantly, the use of such a lining sheet which must be removed and discarded makes it difficult if not impossible to apply the tape to cartons by means of mechanical, and particularly automatic, equipment, yet the use of such equipment for sealing cartons in mass production applications is virtually obligatory.